R/reversemapping.R

In nadiadavidson/goseq: Gene Ontology analyser for RNA-seq and other length biased data

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#Description: Reverses the direction of a bidirectional mapping, removes an entries pointing to NULL
#Notes:
#Author: Matthew Young
#Date Modified: 13/12/2010

reversemapping=function(map){
	tmp=unlist(map,use.names=FALSE)
	names(tmp)=rep(names(map),times=as.numeric(summary(map)[,1]))
	return(split(names(tmp),as.vector(tmp)))
}